Method for the production of a plastic product having a hard plastic component and a soft plastic component, and plastic product produced using said method

Abstract

A plastic product having a hard plastic component and a soft plastic component that adheres to the hard plastic component via at least one boundary surface is produced as follows: initially the soft component is injection molded in an injection molding die. Then the hard component is injection molded. In the plastic product produced in this manner, the soft component is surrounded over at least part of the circumference thereof by the hard component in the circumferential direction about a main demolding direction of the injection molding die. The result is a plastic product, wherein the shape and arrangement of the soft component can be tailored to functional requirements more flexibly.

The invention claimed is: 
     
       1. A method for producing a medical implement comprising a needle and having an exterior hard plastic component ( 7 ) and an interior soft plastic component ( 5 ) which is integral with and adheres to the hard plastic component ( 7 ), comprising
 providing an injection molding die comprising first die parts adapted to and capable of forming a first shape; 
 inserting a needle into and through the first die parts; 
 injection molding a soft plastic in contact with the needle and to form the soft plastic component ( 5 ) in the shape of said first die parts around the needle, the soft plastic component ( 5 ) having a first length; 
 at least partly solidifying said soft plastic of the soft plastic component ( 5 ) and separating said first die parts; 
 injection molding a hard plastic into the injection molding die and over and in contact with both the soft plastic component ( 5 ) and the needle, and adhering the hard plastic to the soft plastic by action of the injection molding; 
 hardening the hard plastic to form the hard plastic component ( 7 ) in contact with and adhered to the soft plastic component, the hard plastic component ( 7 ) having a second length longer than the first length, and separating the resultant medical implement from the injection molding die; 
 wherein the medical implement is an injection needle. 
 
     
     
       2. The method of  claim 1  wherein the soft plastic is a thermoplastic elastomer having a shore hardness of A5-D70, and the hard plastic is a propylene polymer. 
     
     
       3. The method of  claim 2  wherein the thermoplastic elastomer has a shore hardness in the range of A30 to A70. 
     
     
       4. The method of  claim 1  wherein the hard plastic component comprises a thermoplastic. 
     
     
       5. The method of  claim 4  wherein the thermoplastic is polypropylene. 
     
     
       6. The method according to  claim 1  wherein the soft component ( 5 ) comprises a cross-linked TPE. 
     
     
       7. The method of  claim 6 , wherein the soft component ( 5 ) comprises TPE-V. 
     
     
       8. The method of  claim 1  wherein the soft component ( 5 ) comprises a thermoplastic elastomer based on styrene. 
     
     
       9. The method of  claim 8 , wherein the soft component ( 5 ) comprises TPE-S.